Like anyone with two eyes and a stomach, I've longed to visit San Sebastián, the city with the most Michelin stars per capita in Europe. But getting there? Let’s just say there’s a reason gastronomes call traveling to the Basque Country a pilgrimage. From Madrid, where I live, San Sebastián is a five-hour drive, but I don’t have a car. Flights can be wildly expensive, and with no high-speed rail connecting the two cities (yet), a mind-numbing eight-hour train or bus ride seemed inevitable. Then I discovered Blablacar.

Blablacar, a French company that’s been around since 2006, is a ride-share app that lets you carpool with someone traveling from, say, Madrid to San Sebastián or Mexico City to Oaxaca. It’s in 22 countries spanning four continents, and it’s dead simple to use. The interface works like a standard flight search engine: You key in an origin, destination, and departure date, and the app spits out a list of possible drivers and itineraries. To book, all you need is a credit card and a willingness to share a car with a stranger (or four).

For my Basque adventure, I settled on a driver named “Manuel A.” I liked his 4.9-star rating (culled from 75 passenger reviews) and roomy Audi A6. We texted to set a meeting point, and a few days later, there I was—riding shotgun with a 28-year-old line cook born and raised in Madrid.

For those of us who grew up hearing the mantra “don’t talk to strangers,” Blablacar’s business model may seem counterintuitive at best and dangerous at worst, but the numbers indicate otherwise: Blablacar is the world’s largest long-distance ride-sharing app with 60 million registered users. (For comparison’s sake, that’s 10 million more than Uber’s global user base and three million more passengers than British Airways handles each year.)

“We’ve effectively changed consumer behavior on a large scale,” says Verena Butt D’Espous, Blablacar’s head of corporate communications. “Twelve years ago, when the company was founded, everyone thought it was crazy to travel with people they didn’t know. Today, it’s totally mainstream.”

We texted to set a meeting point, and a few days later, there I was—riding shotgun with a 28-year-old line cook born and raised in Madrid.

Fostering trust between passengers and drivers has been central to this attitude shift. To that end, the app allows users to essentially scope one another out ahead of booking. Tap any profile, and in addition to a star rating, you’ll find an “about me” section; a personal photo; and—perhaps most importantly—the user’s preferred level of loquaciousness (“bla” means shy; “bla bla bla” means extra chatty).

With Blablacar, there’s a sense that drivers and passengers are on a level playing field; that the relationship isn’t just transactional. Unlike other ride-share services like UberPOOL and Lyft Line, Blablacar prevents its drivers from making a profit by imposing strict limits on pricing. That keeps rates extremely low for passengers, since you're essentially chipping in for gas and tolls: The 281-mile trip I took with Manuel set me back just 24 euros (about $30), less than half the price of a train ticket and an eighth the price of a flight.

All of this begs the question: Why isn’t it available in the U.S.? Surely there are people who would love to hitch a ride from New York to Chicago, or even ride-share their way across the country in an epic American tour. But it’s not the lack of passengers that Blablacar is worried about so much as the potential lack of drivers. “Cars and gas are cheaper in the U.S., which lowers the incentive for drivers wanting to offset their travel costs,” said D’Espous. “Furthermore, urban areas in the U.S. have fewer public transportation hubs than their European counterparts, which means drivers would have go out of their way to pick up and drop off passengers at their doorsteps, adding a layer of inconvenience.”

If only they’d reconsider. In this era of ever-growing divisiveness, an app like Blablacar might bring people together, literally and figuratively. In a newly published study on the social impacts of carpooling that surveyed approximately 5,000 Blablacar users, 87 percent of those who had tried the service reported “enriching experiences," while 76 percent felt like they helped others by listening or exchanging information, and 51 percent changed their mind on a topic. “Think about that,” D’Espous said. “Total strangers, from all walks of life, having a great time with one another. Now, that’s powerful.”

By the time the whitecaps of the Bay of Biscay came into view, Manu and I had debated Basque separatism, exchanged Spotify usernames, posed for a selfie, and split a tube of Pringles. At first glance, Blablacar may not be the most luxurious way to travel, but getting to know someone new, albeit for a few fleeting hours, is a luxury in itself.